Gas starvation update

[300jk]

I posted maybe 2 weeks ago about our Oliver 1650 gas and very little fuel coming through the needle and seat. A pint in 7 minutes . Today I took off the carb. Took the carb apart. Found nothing restricting flow. Took out brass fitting. No screen in carb. Brake clean in the seat and fuel inlet. Blew through it with compressed air, can blow through it by mouth. What I did notice is the opening in the seat seems small. I used a drill bit to see the size. 5/32. Just bigger than 1/16. I should have stated in original post that this was a reman carb we put on a few years ago and it has never been right. Same problem from day one. To me that orifice in the seat the needle sits in is too small. I can see a pint of gas flowing through that ever in 3 or so minutes. Maybe wrong parts in the reman ? Thoughts ?

 

[M-MAN]

Bore it out a little bigger. Go slow and polish it afterwards with a q tip and polishing compound.

 

[Janicholson]

If fuel flows nicely out the fitting that screws into the carb, You likely have found it. Jim

 

[T.R.K.]

Having just screwed up a lawnmower carburetor jet because it had 'Just slightly lean' fuel mix, I urge caution when drilling the orifice bigger. You might need to enlarge the jet in very small increments until you find that perfect size. (Only .005 larger in my case caused it to go from too lean to way too rich.)

 

[300jk]

Having just screwed up a lawnmower carburetor jet because it had 'Just slightly lean' fuel mix, I urge caution when drilling the orifice bigger. You might need to enlarge the jet in very small increments until you find that perfect size. (Only .005 larger in my case caused it to go from too lean to way too rich.)

I agree that messing with jets is touchy ! This is the needle and seat area. Just lets the gas into the carb. Don’t know if I’d start drilling out jets. I’d be super nervous !

 

[300jk]

If fuel flows nicely out the fitting that screws into the carb, You likely have found it. Jim

I sure hope so Jim. Been a frustrating problem.

 

[M-MAN]

Just for grins I just checked the seat in a small bowl Marvel Shebler for a MF. The 5/32 was tight in it. Have you checked the flow from the line? Could be the screen in the top or bottom of the sediment bowl restricting or the fuel cap not venting?

 

[300jk]

Just for grins I just checked the seat in a small bowl Marvel Shebler for a MF. The 5/32 was tight in it. Have you checked the flow from the line? Could be the screen in the top or bottom of the sediment bowl restricting or the fuel cap not venting?

Excellent flow out of the tank checked right at the fitting going into the carb. Meaning everything right up to the carb flows great. Pint in 10 to 15 seconds or so. Did all my testing when the carb was on the tractor with gas cap off. Called a friend. He has several carbs off 1550, 1650 tractors we are going to compare tomorrow. Will update then.

 

[M-MAN]

Back to the carb then. Measure from the body to the bottom of the float when open. Then measure from the top to the bottom of the bowl. If the float isn't dropping far enough it will restrict flow. Also check the fuel port from the inlet to the seat for casting slag or just not bored deep enough. It's a puzzle!

 

[JOCCO]

I have seen what you are describing and yes, they could have put in a wrong part. Yes, I have bored them out but as others say it can be a risk but look where you're at. I would call carb companies and see if i could get the right one (needle and seat) or buy a kit. See if your friend has any spares or try one of his carbs. Do check your float and pin for issues.

 

[kencombs]

Back to the carb then. Measure from the body to the bottom of the float when open. Then measure from the top to the bottom of the bowl. If the float isn't dropping far enough it will restrict flow. Also check the fuel port from the inlet to the seat for casting slag or just not bored deep enough. It's a puzzle!

Float drop can be critical. So can the length of the needle. Aftermarket or rebuilder parts are often compromises between multiple 'will fit' parts to reduce inventory. Bottom line, it may not be the opening but the needle not clearing the seat far enough when it opens. If the carb has a drop measurement/adjustment try that. If not compare the needle itself to an original, if you have one.

 

[wore out]

I posted maybe 2 weeks ago about our Oliver 1650 gas and very little fuel coming through the needle and seat. A pint in 7 minutes . Today I took off the carb. Took the carb apart. Found nothing restricting flow. Took out brass fitting. No screen in carb. Brake clean in the seat and fuel inlet. Blew through it with compressed air, can blow through it by mouth. What I did notice is the opening in the seat seems small. I used a drill bit to see the size. 5/32. Just bigger than 1/16. I should have stated in original post that this was a reman carb we put on a few years ago and it has never been right. Same problem from day one. To me that orifice in the seat the needle sits in is too small. I can see a pint of gas flowing through that ever in 3 or so minutes. Maybe wrong parts in the reman ? Thoughts ?

It would be interesting to install a temporary clear plastic "sight tube" extending from the bowl drain upwards, secured at the top, and observe what the gasoline level is in the float bowl and how much it drops when the engine is running/working.

In general, fuel inlet valves made for a gravity flow system have a larger "bore" than those designed for systems using a fuel pump.

If your carb proves to be starving for fuel, an easy "workaround" to try would be to install an electric fuel pump.

 

[300jk]

It would be interesting to install a temporary clear plastic "sight tube" extending from the bowl drain upwards, secured at the top, and observe what the gasoline level is in the float bowl and how much it drops when the engine is running/working.

In general, fuel inlet valves made for a gravity flow system have a larger "bore" than those designed for systems using a fuel pump.

If your carb proves to be starving for fuel, an easy "workaround" to try would be to install an electric fuel pump.

Well today I looked at the carbs my friend had. All had the same orifice in the seat. They were off similar tractors. We did a little more adjusting on the floats. Before I was getting a pint every 7 minutes. Now at a pint in 1 minute 40 seconds. I thought they were right, but wasn’t sure. My own fault. Made a mountain out of a mole hill. Should have looked at that first. Not in my right mind recently with my dad’s health issues. Guess my brain is somewhere else. Adjusted the float to 1/4 inch and it flows well. See how it runs in a few days. Thanks to all !

 

[cjunrau]

Well today I looked at the carbs my friend had. All had the same orifice in the seat. They were off similar tractors. We did a little more adjusting on the floats. Before I was getting a pint every 7 minutes. Now at a pint in 1 minute 40 seconds. I thought they were right, but wasn’t sure. My own fault. Made a mountain out of a mole hill. Should have looked at that first. Not in my right mind recently with my dad’s health issues. Guess my brain is somewhere else. Adjusted the float to 1/4 inch and it flows well. See how it runs in a few days. Thanks to all !

Yep. Sometimes we over look the small things. We always assume it’s a big deal, never listening to that small voice in the back ground. Glad you found it.